Optical combiner based on off-axis liquid crystal lens, method of manufacture and display system

Abstract

The present application relates to the technical field of optical devices, and provides an optical synthesizer based on an off-axis liquid crystal lens, a preparation method and a display system, the preparation method comprising: based on a phase encoding principle, obtaining interference exposure parameters corresponding to three primary colors with a target deflection angle and a target focal length as a target, wherein a phase superposition principle is obtained by superimposing an off-axis lens phase distribution and a polarization volume grating phase distribution in the same plane; performing interference exposure processing on the corresponding pre-processed glass substrate respectively according to the interference exposure parameters; curing cholesteric liquid crystal solutions corresponding to the three primary colors on the corresponding glass substrates subjected to the interference exposure processing respectively to obtain three liquid crystal lenses; and performing stacking and packaging on the three liquid crystal lenses to obtain the optical synthesizer. The present application realizes achromatic full-color augmented reality display, while effectively reducing the preparation cost and improving the preparation efficiency.

Description

Technical Field

[0001] This invention relates to the field of optical device technology, and more specifically, to an optical synthesizer, its fabrication method, and a display system based on an off-axis liquid crystal lens. Background Technology

[0002] Augmented Reality (AR) near-eye display technology enables a seamless human-computer interaction experience that blends the virtual and real worlds, demonstrating broad application prospects in various fields such as smart terminals, healthcare, industry, and education. It has become an important research and application direction in the field of optical displays. The Maxwell display method, which projects light directly onto the human retina, offers significant advantages in alleviating eye strain and improving imaging stability, making it a highly promising form of AR near-eye display technology.

[0003] In practical applications of Maxwell display systems, diffractive optics exhibit significant wavelength dependence, leading to substantial chromatic aberration. The insufficient overlap of different colors of light on the same focal plane negatively impacts image quality and user experience. Existing methods for achieving full-color, chromatic aberration-free Maxwell displays largely rely on metal lenses, freeform surfaces, or high-precision, complex fabrication processes, resulting in high manufacturing difficulty, overall high costs, and relatively low production efficiency. As a key component of the Maxwell display system, the optical synthesizer's design and fabrication directly determine the system's size, dispersion characteristics, and image quality. The wavelength dependence of diffractive optics and liquid crystal optics further exacerbates the chromatic aberration problem. Summary of the Invention

[0004] The problem addressed by this invention is how to improve the fabrication quality of optical synthesizers and reduce their fabrication costs.

[0005] To address the aforementioned problems, this invention provides an optical synthesizer based on an off-axis liquid crystal lens, a fabrication method, and a display system.

[0006] In a first aspect, the present invention provides a method for fabricating an optical synthesizer based on an off-axis liquid crystal lens, comprising: Based on the phase encoding principle, with the target deflection angle and target focal length as the target, the interference exposure parameters corresponding to the three primary colors are obtained. The phase superposition principle is obtained by superimposing the phase distribution of the off-axis lens and the phase distribution of the polarizer grating in the same plane. According to the aforementioned interference exposure parameters, interference exposure processing is performed on the corresponding pre-treated glass substrates; The cholesteric liquid crystal solutions corresponding to the three primary colors were respectively solidified on the corresponding glass substrates after interference exposure treatment to obtain three liquid crystal lenses. The three liquid crystal lenses are stacked and packaged to obtain an optical synthesizer.

[0007] Optionally, the interference exposure parameters include the interference angle and the interference grating period; the step of obtaining the interference exposure parameters corresponding to the three primary colors based on the phase encoding principle, with the target deflection angle and target focal length as the targets, includes: Based on the phase encoding principle, according to the Bragg diffraction condition, and combined with the correlation between the interference grating period and the interference angle, the first correlation between the deflection angle and the interference angle is obtained; Using the target deflection angle as the target, the interference angles corresponding to the three primary colors are obtained based on the wavelengths of the three primary colors and the first correlation relationship.

[0008] Optionally, the interference exposure parameters include the feature size of the liquid crystal lens; the step of obtaining the interference exposure parameters corresponding to the three primary colors based on the phase encoding principle, with the target deflection angle and target focal length as the targets, includes: Based on the phase encoding principle, the feature size is introduced to construct a second correlation between the focal length and the feature size; Using the target focal length as the target, the feature size corresponding to the three primary colors is obtained according to the wavelength of the three primary colors and the second correlation relationship.

[0009] Optionally, before performing interference exposure processing on the corresponding pre-treated glass substrates according to the interference exposure parameters, the method further includes: Based on the optical path deviation of the glass substrate, the interference exposure parameters of the three liquid crystal lenses are differentially corrected to obtain the corrected target exposure parameters, which are used to perform interference exposure processing on the corresponding pre-processed glass substrate.

[0010] Optionally, the step of differentially correcting the interference exposure parameters of the three liquid crystal lenses based on the optical path deviation of the glass substrate to obtain the corrected target exposure parameters includes: Select any color of the liquid crystal lens as the focal length reference layer, and based on the substrate parameters of the glass substrate, obtain the corrected reference focal length and reference optical path deviation of the focal length reference layer. The actual optical path deviations of the liquid crystal lenses for the other two colors are calculated based on the substrate parameters of the glass substrate. With the goal of ensuring that the target focal length of the two colored liquid crystal lenses is equal to the reference focal length, the target exposure parameters of the two colored liquid crystal lenses are obtained by reverse calculation based on the corresponding actual optical path deviation.

[0011] Optionally, before performing interference exposure processing on the pretreated glass substrate according to the interference exposure parameters, the method further includes: The glass substrate is subjected to ultrasonic cleaning and ultraviolet ozone disinfection. A photoalignment material is spin-coated onto the surface of a glass substrate after cleaning and disinfection to obtain the pretreated glass substrate. The photoalignment material includes, but is not limited to, azobenzenesulfonic acid dye (SD1) based photoalignment material.

[0012] Optionally, the stacking and packaging of the three liquid crystal lenses to obtain an optical synthesizer includes: The three liquid crystal lenses are stacked and encapsulated in a preset order using refractive index matching adhesive.

[0013] Optionally, the target focal length is set to 3.75 cm.

[0014] Secondly, the present invention provides an optical synthesizer, characterized in that it is fabricated using the optical synthesizer fabrication method based on an off-axis liquid crystal lens as described above.

[0015] Thirdly, the present invention provides a display system including the optical synthesizer as described above.

[0016] The beneficial effects of the optical synthesizer fabrication method based on off-axis liquid crystal lens of the present invention are as follows: Based on the phase encoding principle, the phase distribution of off-axis lens and phase distribution of polarizer grating are superimposed on the same plane. With the target deflection angle and target focal length as design targets, the interference exposure parameters corresponding to the three primary colors are obtained respectively. It is possible to perform independent phase design and parameter optimization for red, green and blue primary colors, significantly reduce the inherent wavelength dependence of diffractive optical devices from the source of optical design, effectively alleviate the problems of obvious color difference and large differences in the propagation paths of different colors of light in Maxwell display system, greatly improve the overlap accuracy of the three primary colors of light on the same focal plane, and provide a reliable parameter basis for realizing high-quality full-color imaging. By employing precise interferometric exposure treatment on pretreated glass substrates using interferometric exposure parameters, microstructures with the designed phase can be directly formed on the substrates. This eliminates the need for traditional complex optical components such as metal lenses and freeform prisms, and also avoids cumbersome processing steps like high-precision milling and polishing. This significantly simplifies the fabrication process and reduces the difficulty of implementation, while ensuring the uniformity and consistency of the phase structure of each substrate. It also reduces stray light and imaging distortion caused by structural defects, thereby effectively improving the overall fabrication quality and optical performance stability of the optical synthesizer. Cholesteric liquid crystal solutions, each matched to one of the three primary colors, are solidified onto the corresponding exposed glass substrates. This fully utilizes the polarization selectivity and wavelength response characteristics of cholesteric liquid crystals to further compensate for phase and optical path differences between different colors, continuously suppressing system dispersion and chromatic aberration, and improving the uniformity of full-color imaging. Furthermore, liquid crystal materials are widely available and inexpensive, and the solidification process is simple and efficient, requiring no stringent high-temperature or high-pressure conditions. This significantly reduces raw material and process costs, improving the fabrication efficiency of the optical synthesizer. By precisely aligning, stacking, and packaging three monochrome liquid crystal lenses, the beam control function of the three primary colors can be integrated into one. While achieving efficient optical synthesis, this makes the display system structure more compact and small, effectively reducing the system size and weight, and better meeting the lightweight and miniaturized requirements of AR near-eye display devices. The stacking and packaging method has low assembly difficulty and strong structural stability, avoiding assembly errors and performance losses introduced by complex assembly, and further ensuring the long-term reliability of the display system.

[0017] This invention solves the technical problems of significant color difference and insufficient color light coincidence accuracy in existing Maxwell display systems by synergistically combining phase design, interference exposure, liquid crystal curing and molding, and stacking packaging. At the same time, it eliminates the dependence on high-precision complex processing technology and expensive optical components. While significantly improving the fabrication quality and imaging effect of optical synthesizers, it effectively reduces the fabrication cost and improves the fabrication efficiency, enabling optical synthesizers based on off-axis liquid crystal lenses to better meet the actual needs of high-performance, low-cost, and large-scale applications in the field of AR near-eye displays. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the light alignment pattern of the CLC PB lens according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a full-color achromatic Maxwell display based on a three-layer stacked CLC PB lens according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the fabrication process of the CLC PB lens according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the second correlation relationship in an embodiment of the present invention. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0020] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0021] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0022] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0023] like Figure 1 and Figure 4 As shown in the figure, an embodiment of the present invention provides a method for fabricating an optical synthesizer based on an off-axis liquid crystal lens, comprising: Step S1: Based on the phase encoding principle, with the target deflection angle and target focal length as the target, obtain the interference exposure parameters corresponding to the three primary colors. The phase superposition principle is obtained by superimposing the phase distribution of the off-axis lens and the phase distribution of the polarizer grating in the same plane.

[0024] Specifically, the optical synthesizer, as the core component of the Maxwell display system, directly determines the beam deflection, focusing effect, and chromatic aberration control capability through its phase distribution. Existing diffractive optical devices exhibit significant wavelength dependence, leading to insufficient focal plane alignment accuracy of the three primary colors and resulting in severe chromatic aberration. Optimizing the phase distribution from the design stage, by utilizing the phase superposition principle to balance the focusing function of off-axis lenses with the deflection and polarization control functions of polarizer gratings, and matching target deflection angles and target focal lengths for each of the three primary colors, provides precise process parameters for the subsequent fabrication of high-precision, chromatic aberration-free liquid crystal lenses, fundamentally alleviating the chromatic aberration problem caused by wavelength dependence. Based on the actual application requirements of AR near-eye display systems, the target deflection angle required for the optical synthesizer—that is, the angle at which the beam is directed onto the human retina—and the target focal length are determined to ensure precise beam focusing and improve image clarity. The center wavelength parameters of the three primary colors—red, green, and blue—are defined as: red: 620-750nm, green: 495-570nm, and blue: 450-495nm, respectively. The target deflection angle and target focal length are converted into corresponding phase distribution information. Using a phase superposition method, the phase distributions of the off-axis lens and the polarizer grating are simultaneously superimposed on the same plane to form a composite phase distribution model adapted to the three primary colors of light. The off-axis lens phase distribution achieves beam focusing, while the polarizer grating phase distribution achieves beam deflection and polarization filtering. Their synergistic effect counteracts the phase deviation caused by wavelength dependence, enabling each layer of optical synthesis devices to simultaneously achieve beam focusing and off-axis deflection. Specifically, this is expressed as follows: , Where φ(x, y) represents the phase function based on the principle of phase superposition, and x and y represent the horizontal and vertical coordinates with the center of the liquid crystal lens plane as the origin, respectively. Indicates the phase distribution of the lens. λ represents the phase distribution of the grating, λ represents the incident light wavelength, corresponding to the center wavelength of the three primary colors, f represents the lens focal length, and Λ represents the grating period.

[0025] Step S2: According to the interference exposure parameters, perform interference exposure processing on the corresponding pre-treated glass substrates respectively.

[0026] Specifically, the glass substrate serves as the carrier for liquid crystal lenses, and its surface flatness, cleanliness, and phase structure accuracy directly affect the optical performance of the liquid crystal lens. Existing technologies rely on complex components such as metal lenses and freeform surfaces, resulting in cumbersome and costly processing, and are prone to structural defects. This invention aims to accurately replicate the composite phase distribution obtained in step S1 onto the glass substrate. Pre-treatment ensures the substrate is compatible with the exposure and liquid crystal curing processes. Interference exposure forms a regular phase microstructure, replacing traditional complex optical components, simplifying the fabrication process, reducing costs, and ensuring phase structure consistency, providing stable substrate support for subsequent liquid crystal molecule orientation. First, the initial glass substrate undergoes pre-treatment such as cleaning, disinfection, and drying to ensure cleanliness, flatness, and improved adhesion. A light-aligning material is then coated onto the cleaned and dried glass substrate to complete the pre-treatment. A two-beam interference exposure system or a Mach-Zehnder interferometer (MZI) is then used to perform interference exposure on the pre-treated glass substrate, recording the light-aligning pattern on the glass substrate.

[0027] Based on the obtained interference exposure parameters corresponding to the three primary colors, the wavelength (e.g., 488 nm laser) and intensity of the laser source are adjusted, and the exposure time is set. The polarization state is adjusted by a half-wave plate, and the beams are split into two beams of equal intensity by a polarization beam splitter. These beams are then converted into left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) beams by a quarter-wave plate, respectively. The incident angle between the two interference beams is adjusted to ensure that the parameters are consistent with the design values. Three pre-treated glass substrates (corresponding to the three primary colors) are placed sequentially on the stage, aligned with the center of the optical path, and the exposure system is started. A lens is introduced into the LCP optical path to form a spherical wavefront, while the RCP optical path maintains a planar wavefront. The two beams interfere in the Fourier plane, forming a composite phase light orientation pattern. When photo-aligned materials are irradiated with polarized light, molecular rearrangement occurs, and their dipole moments tend to align perpendicular to the polarization direction of the incident light, thus forming a spatially varying orientation azimuth distribution on the substrate surface. During exposure, the stage is kept stable to avoid vibrations that could cause interference pattern shifts, ensuring accurate replication of the phase structure. The resulting photo-alignment pattern is shown below. Figure 2 As shown.

[0028] Step S3: The cholesteric liquid crystal solutions corresponding to the three primary colors are respectively solidified on the corresponding glass substrates after interference exposure treatment to obtain three liquid crystal lenses.

[0029] Specifically, cholesteric liquid crystal solutions (CLCs) are configured to adapt to the three primary colors of light, exhibiting polarization and wavelength selectivity. Based on the center wavelengths of the three primary colors, cholesteric liquid crystal solutions adapted to red, green, and blue light are prepared respectively. Specifically, for red light (635nm), the chiral agent concentration is adjusted to match the liquid crystal helical spacing to the 635nm wavelength, achieving selective reflection and phase modulation of red light; for green light (520nm) and blue light (455nm), the chiral agent concentration is adjusted separately to ensure that each solution provides optimal optical modulation only for its corresponding primary color. The liquid crystal solution is coated to uniformly cover the phase microstructure, ensuring consistent liquid crystal layer thickness. Using a blade coating or spin coating process, the prepared three-primary-color cholesteric liquid crystal solutions are coated onto the corresponding glass substrate's phase microstructure surface, with the coating thickness controlled at 1-2μm to ensure uniform coverage of the microstructure without any missed areas or accumulation. The pre-dried substrate is placed in a UV curing machine, aligned with a UV light source, and the curing machine is started. The photoinitiator is excited by the UV light, which triggers the polymerization reaction of the liquid crystal monomers, causing the cholesteric liquid crystal molecules to align in the direction of the phase microstructure on the substrate surface and be permanently fixed. After curing, the substrate is removed and the smoothness of the liquid crystal layer and the presence of defects such as bubbles and cracks are observed under a microscope. If defects are present, the coating and curing are repeated. If there are no defects, three liquid crystal lenses adapted to red light, green light, and blue light are obtained respectively.

[0030] Step S4: Stack and package the three liquid crystal lenses to obtain an optical synthesizer.

[0031] Specifically, the three monochrome liquid crystal lenses need to be integrated into a single unit to achieve coordinated control and optical synthesis of the three primary colors of light, meeting the full-color imaging requirements of the Maxwell display system. Existing technologies suffer from complex assembly processes that easily introduce errors, leading to decreased color matching accuracy and a large, unstable optical synthesizer. By precisely integrating the three monochrome liquid crystal lenses and ensuring the optical axes of each lens coincide and their deflection directions are consistent through stacked packaging, the optical synthesizer structure is simplified, its size reduced, and external moisture and dust are isolated, improving system stability. This ultimately results in an optical synthesizer and display system with full-color control capabilities, suitable for AR near-eye displays.

[0032] Optionally, the stacking and packaging of the three liquid crystal lenses to obtain an optical synthesizer includes: The three liquid crystal lenses are stacked and encapsulated in a preset order using refractive index matching adhesive.

[0033] Specifically, before stacking, ensure the lenses are clean and precisely aligned. Gently wipe the three prepared liquid crystal lenses (red, green, and blue) with a lint-free cloth dampened with anhydrous ethanol to remove dust, fingerprints, and other impurities from the surface, preventing these impurities from affecting the bonding effect and optical performance between the lenses. Construct a precise alignment platform and place the three liquid crystal lenses sequentially on the platform in the order of "green lens → blue lens → red lens" (adjusted according to the optical path design). Observe the optical axis and phase microstructure of each lens using a microscope, and adjust the lens positions to ensure that the optical axes of the three lenses are completely aligned and their deflection directions are consistent, avoiding a decrease in color alignment accuracy due to alignment deviations. A layer of UV adhesive is uniformly coated on the surface (non-substrate side) of each liquid crystal lens. The calibrated lenses are then laminated layer by layer, with slow pressing during the lamination process to expel air between the lenses and prevent stray light from affecting image quality. After lamination, UV light is used for curing to fix the lens assembly and improve structural stability. The packaged optical synthesizer undergoes optical performance testing, including the deflection angle of the three primary colors, focal length, color matching accuracy, and transmittance. If the test fails, the stacking position is adjusted or the assembly is repackaged. After passing the test, it is integrated with components such as the light source, driving circuit, and display panel to obtain a complete optical synthesizer based on three-layer stacked off-axis liquid crystal lenses (CLC PB lenses). The specific structure and display diagram are shown below. Figure 3 As shown.

[0034] This invention, based on the principle of phase encoding, superimposes the phase distribution of an off-axis lens and the phase distribution of a polarizer grating on the same plane. Using the target deflection angle and target focal length as design targets, it obtains the interference exposure parameters corresponding to the three primary colors. This allows for independent phase design and parameter optimization for red, green, and blue primary colors, significantly reducing the inherent wavelength dependence of diffractive optical devices from the optical design source. It effectively alleviates the problems of significant color difference and large differences in the propagation paths of different colors in Maxwell display systems, greatly improving the overlap accuracy of the three primary colors on the same focal plane, and providing a reliable parameter basis for achieving high-quality full-color imaging. By using interference exposure parameters to perform precise interference exposure processing on the pre-treated glass substrate, a microstructure morphology consistent with the designed phase can be directly formed on the substrate. This eliminates the need for traditional complex optical components such as metal lenses and freeform prisms, and also avoids complex processing steps such as high-precision milling and polishing. While significantly simplifying the fabrication process and reducing the difficulty of process implementation, it ensures the uniformity and consistency of the phase structure of each substrate, reducing stray light and imaging distortion caused by structural defects, thereby effectively improving the overall fabrication quality and optical performance stability of the optical synthesizer. Cholesteric liquid crystal solutions, each matched to one of the three primary colors, are solidified onto corresponding exposed glass substrates. This fully utilizes the polarization selectivity and wavelength response characteristics of the cholesteric liquid crystals to further compensate for phase and optical path differences between different colors, continuously suppressing system dispersion and chromatic aberration, and improving the uniformity of full-color imaging. Simultaneously, liquid crystal materials are widely available and inexpensive, and the solidification process is simple and efficient, requiring no stringent preparation conditions such as high temperature and high pressure. This significantly reduces raw material and process costs, improving the fabrication efficiency of the optical synthesizer. By precisely aligning, stacking, and encapsulating three monochromatic liquid crystal lenses, the beam control functions of the three primary colors can be integrated into one unit. This achieves efficient optical synthesis while making the display system structure more compact and smaller, effectively reducing system size and weight, and better meeting the lightweight and miniaturized requirements of AR near-eye display devices. The stacking and encapsulation method has low assembly difficulty and strong structural stability, avoiding assembly errors and performance losses introduced by complex assembly, further ensuring the long-term reliability of the display system.

[0035] This invention solves the technical problems of significant color difference and insufficient color light coincidence accuracy in existing Maxwell display systems by synergistically combining phase design, interference exposure, liquid crystal curing and molding, and stacking packaging. At the same time, it eliminates the dependence on high-precision complex processing technology and expensive optical components. While significantly improving the fabrication quality and imaging effect of optical synthesizers, it effectively reduces the fabrication cost and improves the fabrication efficiency, enabling optical synthesizers based on off-axis liquid crystal lenses to better meet the actual needs of high-performance, low-cost, and large-scale applications in the field of AR near-eye displays.

[0036] Optionally, the interference exposure parameters include the interference angle and the interference grating period; the step of obtaining the interference exposure parameters corresponding to the three primary colors based on the phase encoding principle, with the target deflection angle and target focal length as the targets, includes: Based on the phase encoding principle, according to the Bragg diffraction condition, and combined with the correlation between the interference grating period and the interference angle, the first correlation between the deflection angle and the interference angle is obtained.

[0037] Specifically, based on the Bragg diffraction condition, the relationship between the deflection angle and the incident angle is expressed as follows: , Where, θ out The angle between the diffracted light and the normal to the grating, i.e., the deflection angle, is represented by n. out The refractive index of the exit-side medium is given by m, the diffraction order is given by m (usually an integer), and the wavelength of the incident light in vacuum is given by λ. in θ represents the refractive index of the incident medium. in This represents the angle between the incident light and the grating normal, i.e., the angle of incidence. Because the differences in refraction and diffraction behavior of light of different wavelengths under oblique incidence are amplified, inconsistencies in deflection angles and color separation are more likely to occur, exacerbating color aberration in the system. Therefore, the incident angle theory for the three primary colors is set to 0°. Substituting this into the Bragg diffraction condition, we obtain the expression: sinθ out =λ / Λ.

[0038] Based on the relationship between the interference grating period and the interference angle: , Where λ0 represents the vacuum wavelength of the exposure light source, and θ0 represents the angle between the two interfering beams, i.e., the interference angle.

[0039] By combining the adjusted Bragg diffraction conditions and the correlation between the interference grating period and the interference angle, the first correlation between the deflection angle and the interference angle is obtained, such as... Figure 5 As shown, the black curve represents the achromatic correction condition at a focal length f=3.75cm, expressed as: .

[0040] Using the target deflection angle as the target, the interference angles corresponding to the three primary colors are obtained based on the wavelengths of the three primary colors and the first correlation relationship.

[0041] Specifically, by substituting the target deflection angle, the incident wavelength λ corresponding to the three primary colors, and the obtained corresponding grating period into the first correlation relationship, the interference angles adapted to the red, green, and blue colors are obtained respectively, so that the light of each wavelength can accurately reach the target deflection angle under the corresponding interference angle.

[0042] This embodiment establishes a strict mathematical relationship between the deflection angle and the interference angle by utilizing the phase encoding principle and Bragg diffraction conditions. This enables a quantitative transformation from the optical design target to the physical parameters of the interference exposure, avoiding the control errors caused by traditional empirical parameter settings. It can solve for the matching interference angle and grating period for the three primary color wavelengths, ensuring that the fabricated liquid crystal lens achieves the target focusing effect while maintaining a high degree of consistency in the deflection angles of the three primary colors. This fundamentally suppresses the color difference problem caused by wavelength dependence and significantly improves the imaging accuracy and fabrication consistency of the optical synthesizer.

[0043] Optionally, the interference exposure parameters include the feature size of the liquid crystal lens; the step of obtaining the interference exposure parameters corresponding to the three primary colors based on the phase encoding principle, with the target deflection angle and target focal length as the targets, includes: Based on the phase encoding principle, the feature size is introduced to construct a second correlation between the focal length and the feature size.

[0044] Specifically, in optical synthesizers based on off-axis liquid crystal lenses (CLC PB lenses), feature size is a core structural parameter that determines the lens's focusing capability, deflection efficiency, and chromatic aberration suppression effect. Directly using empirical values ​​to set feature size can easily lead to problems such as large focal length deviations in the three primary colors, diffused focused light spots, and inconsistent deflection angles, exacerbating chromatic aberration and image blurring in the Maxwell display system. By establishing a quantitative correlation (secondary correlation) between macroscopic optical indicators (target focal length) and microscopic structural parameters (feature size) through phase encoding principles, and solving for suitable feature sizes for different wavelengths of red, green, and blue primary colors, a precise mapping from optical design goals to microstructural parameters is achieved. This provides clear structural size constraints for subsequent interferometric exposure processes, ensuring from the source that all three primary colors reach the target focal length while matching the target deflection angle requirements. This effectively reduces chromatic aberration caused by wavelength dependence and improves the imaging accuracy and fabrication consistency of the optical synthesizer.

[0045] Based on the lens phase distribution in the phase encoding principle, a feature size R is introduced, which is expressed as: , After processing, the second correlation between focal length and feature size is obtained, which is expressed as: .

[0046] Using the target focal length as the target, the feature size corresponding to the three primary colors is obtained according to the wavelength of the three primary colors and the second correlation relationship.

[0047] Specifically, by substituting the target focal length and the incident wavelength λ corresponding to the three primary colors into the second correlation relationship, the characteristic dimensions adapted to red, green, and blue colors are obtained respectively, so that light of each wavelength can accurately reach the target focal length under the corresponding characteristic dimensions.

[0048] This embodiment constructs a quantitative second correlation between focal length and feature size through the phase encoding principle, accurately converting the macroscopic optical target (target focal length) into microscopic structural parameters (feature size), avoiding focal length deviation and imaging defects caused by empirical design. The feature size is solved separately for different wavelengths of the three primary colors of light, so that each wavelength of light can strictly match the target focal length, ensuring that the focal planes of the three primary colors of light are highly coincident at the structural level, effectively suppressing the color difference problem of the Maxwell display system. At the same time, the feature size, as a process parameter that can directly guide the interference exposure, improves the controllability and consistency of the manufacturing process, reduces the manufacturing difficulty and cost, and further ensures the imaging quality and performance stability of the optical synthesizer.

[0049] Optionally, before performing interference exposure processing on the corresponding pre-treated glass substrates according to the interference exposure parameters, the method further includes: Based on the optical path deviation of the glass substrate, the interference exposure parameters of the three liquid crystal lenses are differentially corrected to obtain the corrected target exposure parameters, which are used to perform interference exposure processing on the corresponding pre-processed glass substrate.

[0050] Specifically, during the fabrication, cleaning, and handling of the glass substrate, issues such as uneven thickness, surface flatness deviations, and localized refractive index fluctuations are unavoidable. These differences introduce optical path deviations, causing the actual optical path of the subsequently fabricated liquid crystal lenses to deviate from the design value. This leads to problems such as shifts in the focusing position of the three primary colors, inconsistent deflection angles, and diffuse imaging spots, exacerbating color aberration and imaging distortion in the Maxwell display system. By proactively sensing and compensating for optical path deviations in the glass substrate, and by differentially correcting the interference exposure parameters of the three primary color liquid crystal lenses, the designed phase distribution and optical performance can still be accurately matched. This eliminates performance degradation caused by substrate defects at the source of the process, ensuring high consistency in the focal length and deflection angle of the three primary colors, and improving the imaging accuracy and fabrication yield of the optical synthesizer.

[0051] Optionally, the step of differentially correcting the interference exposure parameters of the three liquid crystal lenses based on the optical path deviation of the glass substrate to obtain the corrected target exposure parameters includes: Select any color of the liquid crystal lens as the focal length reference layer, and based on the substrate parameters of the glass substrate, obtain the correction reference focal length and reference optical path deviation of the focal length reference layer.

[0052] Specifically, the liquid crystal lens of the blue light channel is selected as the focal length reference layer, and its reference optical path deviation ΔL is calculated based on the substrate parameters of the blue light glass substrate, such as thickness, refractive index, and surface deviation. B =(n B -n 空 )d, where n空 The refractive index of air is approximately 1, n B Let ΔL be the refractive index of blue light, and d represent the thickness of the glass substrate. B Equivalent focal length deviation Δf converted to blue light B Calculate the corrected reference focal length f of the blue light-reducing lens. B =f 目 -△f B Where f_eye is the target focal length, and f_min is the focal length of the target. B It is the only target focal length that the red and green light lenses need to align, △L B This is the reference optical path deviation for subsequent comparisons.

[0053] The actual optical path deviations of the liquid crystal lenses for the other two colors are calculated based on the substrate parameters of the glass substrate.

[0054] Using the above-mentioned method for obtaining the reference optical path deviation, the actual optical path deviation ΔL corresponding to red light is obtained. R The actual optical path deviation ΔL corresponding to green light G .

[0055] With the goal of ensuring that the target focal length of the two colored liquid crystal lenses is equal to the reference focal length, the target exposure parameters of the two colored liquid crystal lenses are obtained by reverse calculation based on the corresponding actual optical path deviation.

[0056] Specifically, calculate the optical path deviation difference between red and green light relative to blue light: △△L R =△L B -△L R , △△L G =△L B -△L G The optical path deviation difference is converted into a focal length correction value to obtain the actual focal length deviation ΔΔf of the red light. R The actual focal length deviation of green light is △△f G The target focal lengths of red and green light to be corrected are replaced with the correction reference focal length, and the target exposure parameters of red and green light are obtained by using the second correlation relationship, which are the corrected exposure parameters.

[0057] This embodiment selects a single primary color as the focal length reference layer to establish a unified correction reference focal length and reference optical path deviation. Then, based on the actual optical path deviations of the other two color substrates, parameters are back-calculated, achieving differentiated and precise exposure parameter correction. This effectively offsets the optical path error caused by differences in glass substrates, ensuring that the final actual focal lengths of the red, green, and blue liquid crystal lenses are completely consistent, significantly improving color light coincidence accuracy, suppressing system color difference, and simplifying multi-channel synchronous correction logic, thereby improving fabrication stability and imaging quality.

[0058] Optionally, before performing interference exposure processing on the pretreated glass substrate according to the interference exposure parameters, the method further includes: The glass substrate is subjected to ultrasonic cleaning and ultraviolet ozone disinfection.

[0059] Specifically, a 1mm thick optical glass substrate was selected as the substrate material. This specification is a standard fit for liquid crystal lenses used in AR displays, balancing optical transmittance and structural stability. The glass substrate was placed in an ultrasonic cleaning tank containing anhydrous ethanol. Utilizing the cavitation effect of ultrasound, dust, organic oil stains, inorganic microparticles, and other impurities adhering to the substrate surface were removed. After cleaning, the glass substrate surface was dried with high-purity nitrogen to prevent water residue. The dried glass substrate was then placed in an ultraviolet ozone cleaner. Through the synergistic effect of ultraviolet light and ozone, trace amounts of residual organic pollutants on the substrate surface were further removed. Simultaneously, the glass substrate surface was activated, increasing its hydrophilicity and enhancing the adhesion between subsequent photo-alignment materials and the glass substrate, preventing film detachment and edge lifting after film formation.

[0060] A photo-alignment material is spin-coated onto the surface of a glass substrate after cleaning and disinfection to obtain the pretreated glass substrate.

[0061] This embodiment achieves thorough removal of surface impurities and surface activation of the glass substrate through standardized ultrasonic cleaning and ultraviolet ozone disinfection, effectively improving the adhesion between the photo-alignment material and the substrate. Simultaneously, by precisely controlling the spin-coating parameters, a uniform and defect-free photo-alignment film is formed on the glass substrate surface. This provides a clean, flat, and highly responsive functional substrate for the polarization-induced molecular orientation rearrangement during subsequent interference exposure, ensuring the matching degree between the photo-alignment pattern formed by subsequent interference exposure and the phase encoding principle. It avoids distortion of the photo-alignment pattern caused by substrate contamination and film defects, thus laying the foundation for the precise arrangement of cholesteric liquid crystal molecules and improving the consistency and stability of the final liquid crystal lens's optical performance.

[0062] Optionally, the target focal length is set to 3.75 cm.

[0063] Specifically, setting the target focal length precisely to 3.75cm not only aligns with the physiological characteristics of human vision in AR near-eye displays and the imaging requirements of Maxwell displays, allowing the modulated three primary colors of light to be accurately projected onto the human retina for clear imaging and enhancing the user's visual experience; it also provides a unified and quantitative core constraint for the reverse solution of the three primary color interference exposure parameters, ensuring that the design of parameters such as the feature size and grating period corresponding to each wavelength of light revolves around this focal length benchmark. Combined with the differential correction of optical path deviation, a high degree of uniformity in the actual focal length of the three primary colors of light is achieved, effectively avoiding color difference problems caused by inconsistent focal lengths. At the same time, this focal length parameter is compatible with the process control range of the Mach-Zehnder interferometer, reducing the difficulty of parameter solution and process implementation, and ensuring the consistency and stability of the focusing performance of the off-axis liquid crystal lens.

[0064] This invention also provides an optical synthesizer, which is fabricated using the optical synthesizer fabrication method based on off-axis liquid crystal lenses as described above.

[0065] The advantages of the optical synthesizer of this invention over the prior art are the same as those of the optical synthesizer fabrication method based on off-axis liquid crystal lenses described above, and will not be repeated here.

[0066] This invention also provides a display system including the optical synthesizer described above.

[0067] The beneficial effects of the display system of this invention compared to the prior art are the same as those of the optical synthesizer fabrication method based on off-axis liquid crystal lenses described above, and will not be repeated here.

[0068] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for fabricating an optical synthesizer based on an off-axis liquid crystal lens, characterized in that, include: Based on the phase encoding principle, with the target deflection angle and target focal length as the target, the interference exposure parameters corresponding to the three primary colors are obtained. The phase superposition principle is obtained by superimposing the phase distribution of the off-axis lens and the phase distribution of the polarizer grating in the same plane. According to the aforementioned interference exposure parameters, interference exposure processing is performed on the corresponding pre-treated glass substrates; The cholesteric liquid crystal solutions corresponding to the three primary colors were respectively solidified on the corresponding glass substrates after interference exposure treatment to obtain three liquid crystal lenses. The three liquid crystal lenses are stacked and packaged to obtain an optical synthesizer.

2. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 1, characterized in that, The interference exposure parameters include the interference angle and the interference grating period; the process of obtaining the interference exposure parameters corresponding to the three primary colors based on the phase encoding principle, using the target deflection angle and target focal length as targets, includes: Based on the phase encoding principle, according to the Bragg diffraction condition, and combined with the correlation between the interference grating period and the interference angle, the first correlation between the deflection angle and the interference angle is obtained; Using the target deflection angle as the target, the interference angles corresponding to the three primary colors are obtained based on the wavelengths of the three primary colors and the first correlation relationship.

3. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 1, characterized in that, The interference exposure parameters include the feature size of the liquid crystal lens; The method, based on the phase encoding principle, uses the target deflection angle and target focal length as targets to obtain the interference exposure parameters corresponding to the three primary colors, including: Based on the phase encoding principle, the feature size is introduced to construct a second correlation between the focal length and the feature size; Using the target focal length as the target, the feature size corresponding to the three primary colors is obtained according to the wavelength of the three primary colors and the second correlation relationship.

4. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 1, characterized in that, Before performing interference exposure processing on the corresponding pre-treated glass substrates according to the interference exposure parameters, the method further includes: Based on the optical path deviation of the glass substrate, the interference exposure parameters of the three liquid crystal lenses are differentially corrected to obtain the corrected target exposure parameters, which are used to perform interference exposure processing on the corresponding pre-processed glass substrate.

5. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 4, characterized in that, Based on the optical path deviation of the glass substrate, the interference exposure parameters of the three liquid crystal lenses are differentially corrected to obtain the corrected target exposure parameters, including: Select any color of the liquid crystal lens as the focal length reference layer, and based on the substrate parameters of the glass substrate, obtain the corrected reference focal length and reference optical path deviation of the focal length reference layer. The actual optical path deviations of the liquid crystal lenses for the other two colors are calculated based on the substrate parameters of the glass substrate. With the goal of ensuring that the target focal length of the two colored liquid crystal lenses is equal to the reference focal length, the target exposure parameters of the two colored liquid crystal lenses are obtained by reverse calculation based on the corresponding actual optical path deviation.

6. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 1, characterized in that, Before performing interference exposure processing on the pretreated glass substrate according to the interference exposure parameters, the method further includes: The glass substrate is subjected to ultrasonic cleaning and ultraviolet ozone disinfection. A photoalignment material is spin-coated onto the surface of a glass substrate after cleaning and disinfection to obtain the pretreated glass substrate, wherein the photoalignment material includes an azobenzenesulfonic acid dye-based photoalignment material.

7. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 1, characterized in that, The stacking and packaging of the three liquid crystal lenses to obtain an optical synthesizer includes: The three liquid crystal lenses are stacked and encapsulated in a preset order using refractive index matching adhesive.

8. The method for fabricating an optical synthesizer based on an off-axis liquid crystal lens according to claim 1, characterized in that, The target focal length is set to 3.75cm.

9. An optical synthesizer, characterized in that, It is prepared by the optical synthesizer fabrication method based on off-axis liquid crystal lens as described in any one of claims 1 to 8.

10. A display system, characterized in that, Includes the optical synthesizer as described in claim 9.

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